The invention is related to a vehicular display device and a vehicular display system having a display unit that displays visible information and a light projection unit that guides light including the visible information that is displayed on the display unit to a predetermined projection surface, and displaying the visible information as a virtual image.
In a vehicular display device, a head-up display (HUD) having good visibility may be used so as to enable a driver to immediately recognize information having a small amount of the information and a high degree of urgency.
The vehicular head-up display is to guide a light image, which includes visible information to be displayed on a display unit in a display device body, onto a windshield (front glass) of a vehicle and to project the same on a surface of the windshield. When a driver looks ahead in a normal driving posture, the driver can visually recognize not only front scenery and a part of the vehicle, which are seen through the windshield, but also the visible information projected by the head-up display. The visible information that is visually recognized by the driver is formed as a virtual image at the front of the surface of the windshield, for example at a several meter position distant from a viewpoint. Therefore, the driver can recognize the front scenery and the display content of the head-up display by focusing the eyes during the driving.
The head-up display device is generally configured so that a device body thereof is arranged in an instrument panel of the vehicle. The light of the visible information that is displayed on the display unit in the device body is projected towards a projection area such as a windshield, a combiner and the like via a light path including a reflection member such as an enlarging system mirror, so that a virtual image is formed at a predetermined position distant from the viewpoint of the driver.
The related art of the vehicular head-up display device is disclosed in PTL 1, for example. In PTL 1, when an abnormality is detected, a master warning is displayed at a state where the abnormality at one part and the simultaneous abnormalities at a plurality of parts can be distinguished. That is, a content that is displayed by the head-up display and the like has a small amount of information. Therefore, when at least one abnormality occurs, the corresponding abnormality is generally displayed as a master warning in the head-up display and the like. Regarding this, according to PTL 1, when it is detected that one abnormality has occurred, the mater warning is lighted, and when it is detected that a plurality of abnormalities has occurred at the same time, the master warning is blinked, so that they are distinguished.
The same related art is also disclosed in PTL 2. According to PTL 2, a display state on a unified display unit equivalent to the master warning is switched depending on whether the number of an individual display unit turned to the display state is singular or plural.
In a vehicle having the head-up display, it is assumed that when any abnormality of the vehicle is detected, a display of the head-up display is used to issue a warning by displaying a simple symbol such as T, for example. Thereby, the driver can immediately recognize that the abnormality has occurred.
Also, a general vehicle has an instrument unit, which includes a speed meter, a tachometer, a water temperature gauge, a fuel gauge and a plurality of warning lights mounted at places of an instrument panel. Additionally, many vehicles mount thereon a monitor display unit that can display a variety of character strings, figures, images and the like, as required.
Accordingly, when a warning is displayed on the head-up display, the driver can comprehend a specific content relating to the warning by referring to the display of the instrument unit on the instrument panel or the display content of the monitor display unit.
However, all the drivers cannot immediately comprehend a current situation. For example, when the driver is a beginner driver, an old driver or a driver who has not read the manual or just after the driver purchases a new vehicle, it is thought in many cases that the driver does not almost understand functions or operations of the various display devices provided to the vehicle. That is, when an abnormality is detected in the vehicle, so that a warning such as ‘!’ is displayed on the head-up display, if the driver does not care about what the warning means, the driver does not refer to an operation for comprehending a current situation, i.e., the display of an instrument plate and the display content of the monitor display unit.
Also, a variety of instruments and warning lights are present at various places on the instrument unit. Also, in many cases, there are separate display units such as monitor display unit even at a place other than the instrument unit. Therefore, even when the driver recognizes that any abnormality has occurred as regards the warning such as ‘!’ on the head-up display, the driver cannot immediately determine whether the driver should refer to the display of which place unless the driver is familiar with the driving of the vehicle.
Due to the above reasons, even though the vehicle has the head-up display having good visibility, when an abnormality having a high degree of urgency, the driver cannot immediately comprehend a content of the abnormality, so that a serious vehicle malfunction or traffic accident may be caused.
[PTL 1] JP-A-5-185883
[PTL 2] JP-A-3-276836